Template:Needs Translation/
| 函数名
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| float llAtan2( float y, float x );
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| 返回y，x的arctangent2浮点值。
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| •浮动y
•浮动x
与反正切（y/x）类似，只是它利用x&y的符号来确定象限并避免被零除。
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| 注意事项
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| 如果x是正零并且。。。
y为零，返回零。
y为正，返回PI/2。
y为负，-PI/2被返回。
如果x是负零并且。。。
y为正零，返回PI。
y为负零，-PI返回。
y为正，返回PI/2。
y为负，-PI/2被返回。
或者
如果（（字符串）x！=（字符串）0.0&&y==0.0）//负零
返回PI*~-2*（（字符串）y！=（字符串）0.0）；
返回（（y>0）-（y<0））*PI_乘以2；
返回值在范围[-PI，PI]
Search JIRA for related Bugs
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| 示例
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示例1
default
{
state_entry()
{
float num1 = llFrand(100.0);
float num2 = llFrand(100.0);
llOwnerSay("y = " + (string)num1);
llOwnerSay("x = " + (string)num2);
llOwnerSay("The arctangent of y divided by x is " + (string)llAtan2(num1, num2));
}
}
//Function with input of a vector determining the position of a target and returning
//a string with the literal compass-direction of that target towards your position
//by Ramana Sweetwater 2009/01, any use allowed license :-)
//corrected by Patrick Muggins
string compass (vector target)
{
vector source = llGetPos();
list DIRS =["W","NW","N","NE","E","SE","S","SW","W"];
integer index = llCeil(3.5 - (4 * llAtan2(target.y - source.y, target.x - source.x) / PI));
return llList2String(DIRS, index);
}
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